Merge branch 'js/checkout-untracked-symlink' into maint

* js/checkout-untracked-symlink:
  do not overwrite untracked symlinks
  Demonstrate breakage: checkout overwrites untracked symlink with directory

symlinks.c

@@ -223,7 +223,7 @@ int check_leading_path(const char *name, int len)
 	int flags;
 	int match_len = lstat_cache_matchlen(cache, name, len, &flags,
 			   FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
-	if (flags & (FL_SYMLINK|FL_NOENT))
+	if (flags & FL_NOENT)
 		return 0;
 	else if (flags & FL_DIR)
 		return -1;

t/t2021-checkout-overwrite.sh

@@ -0,0 +1,50 @@
+#!/bin/sh
+
+test_description='checkout must not overwrite an untracked objects'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+
+	mkdir -p a/b/c &&
+	>a/b/c/d &&
+	git add -A &&
+	git commit -m base &&
+	git tag start
+'
+
+test_expect_success 'create a commit where dir a/b changed to file' '
+
+	git checkout -b file &&
+	rm -rf a/b &&
+	>a/b &&
+	git add -A &&
+	git commit -m "dir to file"
+'
+
+test_expect_success 'checkout commit with dir must not remove untracked a/b' '
+
+	git rm --cached a/b &&
+	git commit -m "un-track the file" &&
+	test_must_fail git checkout start &&
+	test -f a/b
+'
+
+test_expect_success SYMLINKS 'create a commit where dir a/b changed to symlink' '
+
+	rm -rf a/b &&	# cleanup if previous test failed
+	git checkout -f -b symlink start &&
+	rm -rf a/b &&
+	ln -s foo a/b &&
+	git add -A &&
+	git commit -m "dir to symlink"
+'
+
+test_expect_failure SYMLINKS 'checkout commit with dir must not remove untracked a/b' '
+
+	git rm --cached a/b &&
+	git commit -m "un-track the symlink" &&
+	test_must_fail git checkout start &&
+	test -h a/b
+'
+
+test_done

t/t6035-merge-dir-to-symlink.sh

@@ -17,12 +17,20 @@ test_expect_success SYMLINKS 'create a commit where dir a/b changed to symlink'
 	git commit -m "dir to symlink"
 '
 
-test_expect_success SYMLINKS 'keep a/b-2/c/d across checkout' '
+test_expect_success SYMLINKS 'checkout does not clobber untracked symlink' '
 	git checkout HEAD^0 &&
 	git reset --hard master &&
 	git rm --cached a/b &&
 	git commit -m "untracked symlink remains" &&
-	 git checkout start^0 &&
+	test_must_fail git checkout start^0
+'
+
+test_expect_success SYMLINKS 'a/b-2/c/d is kept when clobbering symlink b' '
+	git checkout HEAD^0 &&
+	git reset --hard master &&
+	git rm --cached a/b &&
+	git commit -m "untracked symlink remains" &&
+	git checkout -f start^0 &&
 	test -f a/b-2/c/d
 '